Actual Charges Severly Higher than stated by Signed Contract

The 1% increase in VAT should have increased my account with R2,53. However, Vodacom increased my account with R50,08. I tried to phone the call center for answers, but they could not assist as per usual. It was escalated to the back office, but out of previous experience with the back office no one ever gets back to you and your ticket is closed with no resolution. I signed a 24 month contract with Vodacom for a specific amount and not even half way through my account is significantly increased. This means that your Vodacom contract means absolutely nothing and they can charge you whatever they like. Stay away from this dangerous provider!